With the advance of the development of printing units suitable for high speed digital printing such as electrophotographic technique, ink jet technique, etc., there has been widely used the single page unit printing procedure control method such that images, graphic forms and characters can be handled in the same way and further characters and graphic forms can be freely enlarged, rotated or transformed, being different from the prior-art method of printing mainly characters. Since the control method as described above has been realized, it is general to develop program languages for describing control procedure, to mount a language translating processing system (so-called interpreter) on a printing unit or a computer, and to convert the language into printing picture elements through the interpreter.
In a single computer, a printing request generated by an application program calls the function of an operating system to actuate a printing unit. Under these conditions, "the page description language" is used to execute the printing procedure, without depending upon hardware such as the resolution, printing method, and the number of printing head dots of the printing unit.
An example of prior-art systems will be described hereinbelow with reference to FIGS. 1A and 1B. Source codes 19 of the page-description language generated by an application program within a computer 6d are translated by a page-description language interpreter 8 to convert the source codes into picture elements used for actual printing. This operation as to whether the page-description language interpreter 8 is executed within the computer 6d as shown in FIG. 1A or within a printing unit 21 as shown in FIG. 1B is different according to the system. In any cases, however, the page-description language interpreter is realized by a single processor in the prior-art system.
Further, there exists a system referred to as print server as one of prior-art systems related to the present invention. In this system, another computer (not shown) is connected to the computer 6d as shown in FIG. 1A, for instance in a network fashion, and the page-description language is rasterized by another computer, instead of the computer 6d which generates a printing processing request. In this prior-art system, the interpreter is realized by a single processor of another computer.
A large capacity of memory is required for conversion of the page-description language into printing picture elements, when executed by the interpreter. Further, where the interpreter is realized by only software, there exists a serious problem in that the processing time is long. In addition, it is apparent that color page printers are expected to be used widely in the near future and high density printing will be required more and more in the case of black-and-white printing. In both the cases, a huge memory space is inevitably necessary. In the case of the color printing, since the printing control procedure is further complicated and therefore the procedure items required for the translation processing program system increase, a long processing time may be required for the execution of the color printing.
To solve the above-mentioned problems, the object of the present invention is to realize a high-speed and high-density processing, which can reduce the contents to be processed by a single processor in accordance with distributed processing such that the respective procedures of the interpreter can be executed by a plurality of processors, to provide such an effect that a huge memory space can be secured as a whole by allowing the plural processors to utilize the respective memory spaces of the respective processors.